Try to type "€" in the chat and the letters will make smaller.
MCPE-4534
Chat bug, letters make smallers (Survival and Creative)
Resolved
Works As Intended
0
(Unassigned)
Unconfirmed
Tablet - iOS - iPod Touch 5
chat, letters, smaller
0.7.2, 0.7.3, 0.7.4, 0.7.5, 0.7.6, 0.8.0, 0.8.1
Retrieved
Unicode characters need to use more pixels, so they look smaller.